Urea-phosphorus compounds

ABSTRACT

The present invention relates to new cyclic organophosphorus esters having the following structures: ##EQU1## where R is aryl or chloroalkyl of 2 to 10 carbon atoms, 
     R&#39; is aryloxy or chloroalkyloxy of 2 to 10 carbon atoms, 
     R&#34; is hydrogen, alkyl, alkenyl, furanyl or aryl of 1 to 15 carbon atoms and substituted aryl forms where the substituent is fluorine, chlorine, bromine, cyano, hydroxyl, alkyloxy, alkylthio or mixtures of such substituents, and 
     Y is O or S. 
     The organophosphorus compounds have biological activity and are also useful as fire retardants, and as lead scavengers in gasoline.

The present patent application is a continuation-in-part of Ser. No. 385,933, filed Aug. 6, 1973, which application has been abandoned.

The present invention relates to new cyclic organophosphorus esters.

Organophosphorus acids are obtained by ringopening hydrolysis reactions of the cyclic esters of this invention.

The general method for the production of the novel cyclic esters is in accordance with the following equation: ##EQU2## where R is aryl or chloroalkyl of 2 to 10 carbon atoms,

R' is aryloxy or chloroalkyloxy of 2 to 10 carbon atoms,

R" is hydrogen, alkyl, alkenyl, furanyl or aryl of 1 to 15 carbon atoms and substituted aryl forms where the substituent is fluorine, chlorine, bromine, cyano, hydroxyl, alkoxy, alkylthio or mixtures of such substituents, and

Y is O or S.

A specific example is the formation of 1,4-dimethyl-3-(4-hydroxy-3-methoxyphenyl)-2-phenoxy-1,4,2-diazophospholidin-5-one-2-oxide from the reaction of 1,3-dimethylurea and vanillin with triphenyl phosphite. ##SPC1##

When cyclic esters of this invention are hydrolyzed, the products are the corresponding open-chain phosphonic acids: ##EQU3## where R is aryl or chloroalkyl of 2 to 10 carbon atoms

R" is alkyl, alkenyl, furanyl or aryl of 1 to 15 carbon atoms and substituted aryl forms where the substituent is fluorine, chlorine, bromine, cyano, hydroxyl, alkyloxy, alkylthio or mixtures of such substituents, and

Y is O or S.

A specific example of a phosphonic acid is α-(1,3-dimethylureido)-4-hydroxy-3-methoxybenzylphosphonic acid, ##SPC2##

Formation of the cyclic products of this invention is usually initiated when a mixture of the three reactants, preferably in an inert solvent such as toluene or chlorobenzene, is warmed to about 70°C. The reaction is usually complete after an hour at 80°-120°C., but warming at higher or lower temperatures is sometimes advantageous. Gradual addition of the aldehyde reactant to a stirred mixture of the phosphorous ester and 1,3-dimethylurea reactants in a solvent at reaction temperature, usually from about 70° to 120°C., may facilitate control of heat of reaction.

The cyclic products may be isolated from the reaction mixtures and purified by standard techniques before being subjected to hydrolysis to the corresponding acids. However, it is frequently more convenient, particularly with the cyclic phosphonates, to treat the crude, unisolated product in the reaction mixture with the required amount of water and then stir and warm the mixture until the desired hydrolysis is complete. The low solubility of the free acids in the reaction mixtures usually makes the acids easier to isolate than the parent cyclic structures.

Specific examples showing the preparation and isolation of representative compounds of the present invention are set forth herewith, but are not limitative of the scope of the invention.

EXAMPLE 1 3-(2,4-Dichlorophenyl)-1,4-dimethyl-2-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide. ##EQU4##

A solution of 0.3 mole each of diphenyl phenylphophonite, 2,4-dichlorobenzaldehyde, and 1,3-dimethylurea in 150g of toluene is stirred under N₂ and warmed at 100°-110° for 2 hr. The resulting solution has ³¹ P nmr peaks at -30.6 and -26.3 ppm ˜2:1 areas). The solvent and most of the by-product phenol are removed by stripping to 120°/1mm, and the residue is diluted with ether which causes separation of white solid (I), mp 204°-206° (from CH₃ CN). Additional solid (II), mp 205°-207.5°, is isolated from the filtrate. There is marked depression of the mixed melting point of I and II and appreciable differences in their nmr spectra. For I: ³¹ P nmr -28.9 ppm (in CDCl₃), -38.6 ppm (in CF₃ CO₂ H); ¹ H nmr (CDCl₃) δ 7.3 (m, 8, aryl), 5.2 (d, 1, J = 22Hz, PCH), 3.1 (s, 3, CH₃ NCH), 2.9 (d, 3, J = 8Hz, PNCH₃); ms 370(6) (molecular ion), 368(10) (molecular ion), 335(10), 333(25), 311(6), 278(23), 276(100), 186(38), 124(43), 77(29). For II: ³¹ P nmr -25.0 ppm (in CDCl₃), -32.9 ppm (in CF₃ CO₂ H); ¹ H nmr (CDCl₃) δ 7.6 (m, 8, aryl), 5.2 (d, 1, J = 9Hz, PCH), 2.9 (s, 3, CHNCH₃), 2.85 (d, 3, J = 8Hz, PNCH₃) (decoupling from ³¹ P converted the doublets at 5.2 and 2.85 ppm to singlets); ms 370(1), 368(1 ), 335(12), 333(66), 311(2), 278(13), 276(100), 186(29), 124(32), 77(13).

Anal.(II) Calcd for C₁₆ H₁₅ N₂ Cl₂ O₂ P: C, 52.05; H, 4.10; Cl, 19.21; N, 7.59; P, 8.39. Found: C, 52.33; H, 4.14; Cl, 18.82; N, 7.50; P, 8.31.

EXAMPLE 2 1,4-Dimethyl-2-(4-methylphenoxy)-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU5##

Benzaldehyde, 0.5 mole, is added dropwise to a solution of 0.5 mole of 1,3-dimethylurea and 0.5 mole of tris(p-tolyl) phosphite in 100g of benzene as the solution was warmed from 60°-90°. Warming is continued at 90° for 3 hr, giving a reaction mixture having ³¹ P nmr peaks at -24.2 and -21.9 ppm (˜6:1 areas). The solvent and most of the by-product p-cresol are removed by stripping to 120°/0.5mm, and the remaining yellow, viscous oil is dissloved in acetone. A solid that separates is recrystallized from acetone to give a white solid: mp 126.5°-128°; ³¹ P nmr -24.2 ppm; ¹ H nmr δ6.9-7.5 (m, 9, aryl), 4.6 (d, 1, J = 19Hz, PCH), 2.9 (d, 3, J = 8Hz, PNCH₃), 2.7 (s, 3, NCH₃), 2.3 (s, 3, CH₃); ms 330(50) (molecular ion), 273(1), 244(4), 239(6), 223(27), 182(4), 166(100), 118(49), 107(5), 91(17), 77(14), 60(42).

Anal. Calcd for C₁₇ H₁₉ N₂ O₃ P: C, 61.18; H, 5.80; N, 8.48; P, 9.38. Found: C, 61.81; H, 5.67; N, 8.33; P, 9.33.

EXAMPLE 3 1,4-Dimethyl-2,3-diphenyl-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU6##

A solution of 0.3 mole each of bis(chloropropyl) phenylphosphonite, 1,3-dimethylurea, and benzaldehyde in 100g of toluene is warmed at 105°-110° for 1.5 hr, giving a light yellow reaction mixture in which about half of the phosphorus detectable by nmr had a chemical shift at -25.9 ppm. Stripping to 107°/0.5mm followed by dilution with ether and filtration gives 14.8g of white solid: mp 132°-138° (141.5°-143.5° from tetrahydrofuran-ether); ³¹ P nmr -25.6 ppm; ¹ H nmr δ 7.3 and 7.6 (m, 10, aryl), 4.6 (d, 1, J = 6Hz, CH), 2.9 (d, 3, J = 8Hz, CH₃ NP), 2.8 (s, 3, CH₃ NCH) (phosphorus decoupling converted both doublets to singlets); mass spectrum (70 eV) m/e(rel intensity) 300(27) (molecular ion), 243(67), 228(35), 166(15), 124(30), 118(100), 77(38), 60(15).

Anal. Calcd for C₁₆ H₁₇ N₂ O₂ P: C, 63.98; H, 5.70; N, 9.33; P, 10.31. Found: C, 63.70; H, 5.75; N, 9.06; P, 10.40.

EXAMPLE 4 1,4-Dimethyl-3-(3,4-dichlorophenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-thione-2-oxide ##EQU7##

A solution of 0.3 mole each of 1,3-dimethylthiourea, 3,4-dichlorobenzaldehyde, and triphenyl phosphite in 75g of toluene is warmed at 120°-125° for 1.25 hr, giving a yellow solution having ³¹ P nmr signals at -27.5 and -24.7 ppm (˜5:1 areas). The reaction mixture is stripped to 110°/0.5mm to remove the solvent and most of the by-product phenol. Two-thirds of the resulting yellow oil is diluted with ether, kept at 5° for 12 hr and filtered, giving 35.2g of white solid: mp 125°-126° (from butyl acetate); ³¹ P nmr -26.6 ppm; ¹ H nmr δ 7.2 (m, 8, aryl), 4.7 (d, 1, J = 18Hz, CH), 3.1 (d, 3, J = 7Hz, CH₃ NP), 3.1 (d, 3, J = 1Hz, CH₃ NCH; ir(KBr) 2.9(m), 6.24(w), 6.68(s), 7.20(m), 7.53(s), 7.87(s), 8.37(s), 10.68μ(vs); ms 400 and 402(100) (molecular ions), 327 and 329(8), 307 and 309(3), 298 and 300 (72), 186 and 188(69), 159 and 161(50).

Anal. Calcd for C₁₆ H₁₅ Cl₂ N₂ O₂ PS: C, 47.89; H, 3.77; Cl, 17.67; N, 6.98; P, 7.72; S, 7.99. Found: C, 47.90; H, 3.87; Cl, 17.93; N, 6.94; P, 7.71; S, 7.93.

The remaining one-third of the yellow oil is dissolved in 100ml of acetonitrile and 15g of H₂ O, and this solution is refluxed for 1 hr. After standing 15 hr at room temperature, the reaction mixture is filtered, and the solid is extracted with hot acetonitrile, giving 17.8g. Recrystallization from acetic acid-water gives 13.5g of α-(1,3-dimethylthioureido)-3,4-dichlorobenzylphosphonic acid: white solid; mp 178° -179° dec; ³¹ P nmr (CD₃ SOCD₃) -15.1 ppm (d, J = 24Hz); ¹ H nmr δ8.5 (s, 3, HO and NH), 7.7 (m, 3, aryl), 7.2(d, 1, J = 24Hz, CH), 3.1 and 3.0 (s, 6, CH₃); ir(KBr) 3.02μ(m), 3.51(m), 6.45(s, 6.78(m), 7.32(s), 7.90(s); acidity, 2.00 equiv/mole, pK.sub. 1 = 3.20, pK₂ = 8.65.

Anal. Calcd for C₁₀ H₁₃ Cl₂ N₂ O₃ PS: C, 34.99; H, 3.82; Cl, 20.66; N, 8.16; P, 9.02; S, 9.34. Found: C, 34.89; H, 4.25; Cl, 20.84; N, 8.15; P, 8.81; S, 9.25.

EXAMPLE 5 3-(4-Cyanophenyl)-1,4-dimethyl-2-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU8##

A mixture of 0.12 mole each of 4-cyanobenzaldehyde, 1,3-dimethylurea, and diphenyl phenylphosphonite in 150ml of toluene is warmed at reflux (112°) for 3.5 hr and then stripped to 120°/10mm, leaving a viscous, light yellow oil having ³¹ P nmr peaks at -31.2 and -25.7 ppm (˜2:1 areas). Dilution of the oil with ether results in separation of a solid from which two isomers are isolated by fractional crystallization. Isomer I: mp 176°-179°; ³¹ P nmr (CDCl₃) -30.6 ppm; ¹ H nmr δ7.3 (m, 9, aryl), 5.1 (d, 1, J = 22Hz, PCH), 3.0 (s, 3, NCH₃), 2.95 (d, 3, J = 8Hz, PNCH₃). Isomer II: mp 180°-182.5°; ³¹ P nmr -26.7 ppm; ¹ H nmr δ7.8 (m, 9, aryl), 4.7 (d, 1, J = 7Hz, PCH), 2.9 (s, 3, NCH₃), 2.9 (d, 3, J = 8Hz, PNCH₃). There is a sharp depression of the mixed melting point of I and II.

EXAMPLE 6. 2-(2-Chloroethoxy)-1,4-dimethyl-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU9##

A mixture of 88.0g (1.0 mole) of 1,3-dimethylurea, 269.5g (1.0 mole) of tris(2-chloroethyl) phosphite, and 106.1g (1.0 mole) of benzaldehyde is stirred under nitrogen and warmed at 103°-106° for 3.5 hr, giving a light yellow solution: ³¹ P nmr -139.0, -28.3, -22.8 (area ratio ˜1:8:2). The by product ethylenechlorohydrin is stripped off to 105°/0.1mm, and 150ml of benzene is added. Solid separates as the reaction mixture cools. Recrystallization from acetonitrile gives 50.1g, mp 134°-135.5°. A second recrystallization from acetonitrile gives a white solid: mp 136°-137°; ³¹ P nmr -28.5 ppm; ¹ H nmr δ7.3 (m, 5, aryl), 4.6 (d, 1, J = 19Hz, CH), 4.3 (m, 2, OCH₂), 3.7 (m, 2, CH₂ Cl), 2.9 (d, 3, J = 8Hz, PNCH₃), 2.8 (s, 3, CH₃ NCH); ir(KBr) 3.42(m), 5.78(s), 6.90(m), 7.22(m), 7.95(vs); mass spectrum (70 eV) m/e(rel intensity) 302(26) (molecular ion), 273(2), 245(9), 239(40), 216(6), 182(8), 166(5), 118(100), 91(14).

Anal. Calcd for C₁₂ H₁₆ ClN₂ O₃ P: C, 47.61; H, 5.33; Cl, 11.71; N, 9.25; P, 10.23. Found: C, 47.69; H, 5.25; Cl, 11.69; N, 9.34; P, 10.38.

The filtrates are combined and treated with 30g of water at reflux for 0.5 hr. Filtration of the warm reaction mixture and then extraction of the solid with warm acetonitrile gives 50.9g of α-(1-3-dimethylureido) benzylphosphonic acid: mp 178°-180° dec; ³¹ P nmr (CD₃ SOCD₃) -18.2 ppm; ¹ H nmr δ10.1 (broad, 3, HO and NH), 7.3 (m, 5, aryl), 5.8 (d, 1, J = 24Hz, CH), 2.9 (s, 3, CH₃), 2.6 (s, 3, CH₃).

EXAMPLE 7 1,4-Dimethyl-3-(4-hydroxy-3-methoxyphenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide ##SPC3##

A mixture of 76.1g (0.5 mole) of vanillin, 44.0g (0.5 mole) of 1,3-dimethylurea, and 155.0g (0.5 mole) of triphenyl phosphite in 200g of benzene is stirred under N₂ and warmed at reflux (95°) for 1 hr. About half of the benzene is distilled to give a yellow solution: ³¹ P nmr -25.3 ppm. The reaction mixture solidifies while standing for several days. Additional benzene is added to aid in breaking up the solid. Filtration gives 64.0g of slightly yellow solid. Recrystallization of an 11.0g portion from acetonitrile gives 5.2g of white solid: mp 168°-170°; ³¹ P nmr -24.5 ppm; molecular weight 362 (mass spectrum) (theory 362).

Anal. Calcd for C₁₇ H₁₉ N₂ O₅ P: C, 56.35; H, 5.29; N, 7.73; P, 8.55. Found: C, 56.03; H, 5.10; N, 7.66; P, 8.34.

EXAMPLE 8 α -(1,3-Dimethylureido)benzylphosphonic acid ##EQU10##

A mixture of 155.2g (0.5 mole) of freshly distilled triphenyl phosphite, 53.0g (0.5 mole) of benzaldehyde, and 44.1g (0.5 mole) and 1,3-dimethylurea in 150g of toluene is stirred under N₂ and warmed. Heat of reaction is noticeable at ˜80°, and cooling is used for ˜10 minutes to keep the temperature below 85°. The reaction mixture is warmed at reflux (117°) for 1.25 hr and then stripped to 140° /0.15 mm to give the ester product 1,4-dimethyl-3-phenyl-2-phenoxy-1,4,2-diazaphospholidin-5-one-oxide which solidifies when cooled, ³¹ P nmr -24.4 ppm.

The preceding compound is dissolved in acetonitrile (150ml) and 36.0g (2.0 moles) of distilled water, and the solution is warmed at reflux for several hours. Solid that forms during warming is separated by filtration of the hot reaction mixture, giving 104.5g (80.9% yield), mp 178°-181° (with foaming). Recrystallization of a portion from isopropyl alcohol gives a white solid: mp 181°-182° (with foaming); ³¹ P nmr (DMSO-d₆) -18.1 ppm (d, J_(P-H) = 24 Hz); ¹ H nmr δ9.6 (broad singlet, 3, OH and NH), 7.3 (m, 5, C₆ H₅), 5.7 (d, 1, J_(H-P) = 24 Hz), 2.9 (s, 3, NCH₃), 2.6 (s, 3, NCH₃); acidity, 2.01 equiv/mole, pK₁ = 2.20, pK₂ = 8.62.

Anal. Calcd for C₁₀ H₁₅ N₂ O₄ P: C, 46.51; H, 5.85; N, 10.85; P, 11.99. Found: C, 46.60; H, 5.78; N, 10.79; P, 12.10. Phenol, 109.9g (78% yield), is isolated from the distillate and filtrate.

EXAMPLE 9 1-(1,3-Dimethylureido)-2-ethylhexylphosphonic acid ##EQU11##

A mixture of 88.1g (1.0 mole of 1,3-dimethylurea, 269.5g (1.0 mole) of tris(2-chloroethyl) phosphite, and 135g (1.05 moles) of 2-ethylhexaldehyde is warmed at 105°-110° for 2 hr, giving a clear colorless solution containing 2-(2-chloroethoxy)-1,4-dimethyl 3-(3-heptyl)-1,4,2-diazaphospholidin-5-one-2-oxide, as an intermediate ester product, ³¹ P nmr 31 30.8. Four-fifths of the reaction mixture is dissolved in 200ml of cyclohexane containing 34.5g of H₂ O, and the mixture is warmed at 82° for 0.5 hr. Filtration after cooling, and extraction of the solid with hot acetonitrile gives 54.7g of white solid (100.8g more separates from the filtrate while standing): mp 184°-186° dec; ³¹ P nmr (CD₃ SOCD₃) -23.5 ppm(m); ¹ H nmr δ9.8 (broad, 2, OH), 4,4 (d of d, 1, J = 10 and 20Hz, PCH), 2.7 (s, 3, NCH₃), 2.5 (s, 3, NCH₃), 0.5 - 2.0 (broad, 15, hexyl); acidity 1.985 equiv/mole, pK₁ = 1.76, pK₂ = 5.29.

Anal. Calcd for C₁₁ H₂₅ N₂ O₄ P: C, 47.13; H, 8.99; N, 9.99; P, 11.05. Found: C, 47.41; H, 9.59; N, 10.03; P, 11.34.

EXAMPLE 10 α-(1,3-Dimethylureido)-4-hydroxy-3-methoxybenzylphosphonic acid ##SPC4##

A solution of 10.0g of 1,4-dimethyl-3-(4-hydroxy-3-methoxyphenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide in 90g of acetonitrile and 10g of water was warmed at reflux for 0.5 hr, and then most of the solvent was allowed to evaporate. The residue was recrystallized twice from ethanol to give 4.6g of white solid: mp 183°-184° (dec); ³¹ P nmr (CD₃ SOCD₃) -18.6 ppm (d, J = 24Hz); ¹ H nmr δ 10.0 (broad, 3, Oh), 5.7 (d, 1, J = 24Hz, CH), 3.8 (s, 3, OCH₃), 2.9 (s, 3, NCH₃), 2.7 (s, 3, NCH₃); 6.7-7.3 (m, 4, aryl and HN).

EXAMPLE 11 1-(1,3-Dimethylureido)-3-(methylthio)propylphosphonic acid ##EQU12##

When a mixture of 0.5 mole each of 1,3-dimethylurea, triphenyl phosphite, and 3-methylthiopropionaldehyde in 100g of toluene is warmed to 75°, a reaction is initiated and the temperature increases rapidly to 120°. After further warming at 105° for 1 hr, the resulting yellow product has a ³¹ P nmr signal at -28.2 ppm for the cyclic ester, 1,4-dimethyl-3-(2-methylthioethyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide. The above product is then employed in a toluene solution from which byproduct phenol is removed by stripping to 110° /1 mm, after which one-third of the residue is dissolved in 75ml of acetonitrile and 10g of water, and this solution is refluxed for 3 hr. The reaction mixture is allowed to evaporate to dryness, and the residue is extracted with ether and then with hot acetonitrile and recrystallized twice from acetic acid to give a white solid: mp 164.5°-167°; ³¹ P nmr (DMSO-d₆) -21.4 ppm; ¹ H nmr 9.6 (broad, 2, OH), 4.5 (m, 1, PCH), 2.8 (s, NCH₃), 2.6 (s, NCH₃), 2.0 (s, SCH₃), 1.9-2.6 (m, CH₂ CH₂ S).

EXAMPLE 12 1-(1,3-Dimethylureido)-3,7-dimethylocta-2,6-dienyl-1-phosphonic acid ##EQU13##

A mixture of 44.0g (0.5 mole) of 1,3-diemthylurea, 135g (0.5 mole) of tris(2-chloroethyl) phosphite, and 76.1g (0.5 mole) of citral is warmed at 95°-105° for 3.75 hr., giving the intermediate ester 2-(2-chloroethoxy)-1,4-dimethyl-3-(2,6-dimethylhepta-1,5-dienyl)-1,4,2-diazaphospholidin-5-one-2-oxide, having a ³¹ P nmr peak at -28.3 ppm. Water, 54g (3.0 moles), is added, and warming is continued at 75°-90° for 1 hr more. The reaction mixture is diluted with 200ml of acetonitrile and allowed to stand at room temperature for 12 hr. Solid that forms is extracted twice with hot acetonitrile, giving 17.6g, mp 155°-157° dec. Recrystallization from acetic acid gives a white solid: mp 157°-159° dec; ³¹ P (CD₃ SOCD₃) -20.8 ppm (m); acidity 1.97 equiv/mole, pK₁ = 3.85, pK₂ = 9.29.

Anal. Calcd for C₁₃ H₂₅ N₂ O₄ P: C, 51.29; H, 8.28; N, 9.20; P, 10.18. Found: C, 51.03; H, 8.75; N, 9.05; P, 10.15.

EXAMPLE 13 [α-(1,3-Dimethylureido)-2,4-dichlorobenzyl]phenylphosphinic acid ##EQU14##

A suspension of 14.4g (0.039m) of 3-(2,4-dichlorophenyl)-1,4-dimethyl-2-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide in 120ml of ethanol is stirred as 0.04m of NaOH (1.0 molar solution) is added dropwise. The solid starting material goes into solution and then another solid separates after a few minutes. This is separated by suction filtration, washed with ethanol, and then extracted with hot acetonitrile to give the sodium salt, a white solid, mp ˜294° dec.; ³¹ P nmr (D₂ O) -25.8 ppm; ¹ H nmr δ7.05 - 8.15 (m, 8, aryl), 5.8 (d, 1, J = 14Hz, PCH), 3.0 (s, 3, NCH₃), 2.6 (s, 3, NCH₃). A solution of 8.5g of this salt in 200ml of H₂ O is stirred as 5g of trifluoroacetic acid is added dropwise. Solid separates immediately. It is recrystallized from acetonirile to give a white solid, mp 178° ³¹ P nmr (DMSO-d₆) -31.7 ppm; ¹ H nmr δ 7-8.5 (m, 8, aryl), 6.1 (d, 1, J = 14Hz, PCH), 2.9 (s, 3, NCH₃), 2.5 (s, 3, NCH₃); acidity 0.98 equiv/mole, pK_(a) 4.12.

Anal. Calcd for C₁₆ H₁₇ Cl₂ N₂ O₃ P: C, 49.63; Cl, 18.31; N, 7.23; P, 8.00 Found: C, 49.72; H, 4.49; Cl, 18.58; N, 7.29; P, 8.12.

EXAMPLE 14 1,4-Dimethyl-3-(2-furanyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU15##

Under conditions similar to those used for the preparation of Example 7 except that furfural is used as the aldehyde reaction, the subject compound is obtained as a white solid: mp 129°-131°; ³¹ P nmr (CDCl₃) - -20.9 ppm; ¹ H δ 6.4-7.4 (m, δ, aryl), 4.8 (d, 1, J = 20Hz, CH), 3.0 (d, 3, J = 8Hz, CH₃ NP), 2.8 (s, 3, CH₃ NCH); ms m/e 306(29) molecular ion, 213(6), 156(100), 108(24).

EXAMPLE 15

When a portion of the product of Example 14 is dissolved in acetonitrile and the solution is treated with water and warmed, (1,3-dimethylureido) (2-furanyl)methylphosphonic acid is produced.

EXAMPLE 16 1,4-Dimethyl-2-phenyl-1,4,2-diazaphospholidin-5-thione-2-oxide ##EQU16##

A mixture of 31.2g (0.3 mole) of 1,3-dimethylthiourea, 88.3g (0.3 mole) of diphenyl phenylphosphonite and 13.5g of paraformaldehyde in 80g of toluene is stirred under N₂ and warmed at reflux for 3 hr. After standing overnight, the reaction mixture is filtered to remove a small amount of solid, and the filtrate is stripped to 120°/0.2mm. The residue is extracted twice with ether and once with cyclohexane, and the remaining insoluble material is recrystallized twice from acetonitrile to give 32g (44% yield) of white solid: mp 170°-172°; ³¹ P nmr -31.5 ppm; ¹ H nmr δ 7.6 (m, 5, C₆ H₅), 3.88 (d, 1, J = 11.6Hz, HCH), 3.85 (d, 1, J = 8.2Hz, HCH), 3.4 (d, 3, J = 1.2Hz, CH₂ NCH₃), 3.0 (d, 3, J = 7.2Hz, PNCH₃); ms 240 (molecular ion).

Anal. Calcd for C₁₀ H₁₃ N₂ OPS: C, 49.98; H, 5.45; N, 11.66; P, 12.89; S, 13.34. Found: C, 50.00; H, 5.33; N, 11.67; P, 12.92; S, 13.20.

EXAMPLE 17 1,3-Dimethylthioureidomethyl)phenylphosphinic acid ##EQU17##

A mixture of 1,4-dimethyl-2-phenyl-1,4,2-diazaphospholidin-5-thione-2-oxide and 40ml of ethanol is stirred as 0.035m of NaOH (10 molar solution) is added dropwise. Solid dissolves during the NaOH addition. The reaction mixture is allowed to evaporate to dryness, and the residue is washed with ether to give crude sodium salt, a white solid: mp 242°-260°; ³¹ P nmr (D₂ O) -24.7 ppm; ¹ H nmr δ 7.2 (m, 5, C₆ H₅), 3.9 (d, 2, J = 8Hz, CH₂), 3.0 (s, 3, CH₃), 2.9 (s, 3, CH₃). A 5.0g portion is dissolved in 80 ml of distilled water, and the solution is stirred as 2.2g of trifluoroacetic acid is added dropwise. A white solid that separates after a few minutes is recrystallized from acetonitrile: mp 161°-163°; ³¹ P nmr (DMSO-d₆) -31.2 ppm; ¹ H nmr δ 7.3 - 8.4 (m, 6, C₆ H₅ and OH), 4.3 (d, 2, J = 7Hz, CH₂), 3.1 (s, 3, CH₃), 2.9 (s, 3, CH₃); acidity 0.990 equiv/mole, pKa = 4.05.

EXAMPLE 18 1,4-Dimethyl-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide ##EQU18##

A mixture of 22.0g (0.25 mole) of 1,3-dimethylurea, 8.6g of paraformaldehyde, and 77.5g (0.25 mole) of triphenyl phosphite in 100g of benzene is warmed to 80°where heat of reaction is evident, and cooling is needed for a few minutes to keep the temperature below 84°. The reaction mixture is warmed at reflux for 1 hr and then stripped to 105° 10.5 mm to remove solvent and part of the by-product phenol. Solid that separates upon cooling is isolated by filtration and then recrystallized three times from diglyme to give 23.2g of white solid ester: mp 124°-128°; ³¹ P nmr -23.4 ppm; ¹ H nmr δ 7.2 (m, 5, aryl), 3.6 (d, 2, J = 15Hz, CH₂), 2.9 (d, 3, J = 8Hz, CH₃ NP), 2.9 (d, 3, J = 1Hz, CH₃ NCH.sub. 2) (decoupling from phosphorus converts all three doublets to singlets); mass spectrum (70 eV) m/e (rel intensity) 240(63) (molecular ion), 211(2), 183(1), 147(12), 140(99), 90(100)56(5), 47(23), 42(86).

Anal. Calcd for C₁₀ H₁₃ N₂ O₃ P: C, 50.00; H, 5.46; N, 11.66; P, 12.89. Found: C, 49.98; H, 5.63; N, 11.63; P, 12.70.

EXAMPLE 19 (1,3-Dimethylureido)methylphosphonic acid ##EQU19##

A solution of 12.0g (0.05 mole) of the product of Example 18 in 90g of acetonitrile and 10g of water is refluxed for 1 hr. Solid that separates upon cooling is stirred in boiling acetonitrile, and the mixture is filtered while hot to give 7.4g (82%) of white solid: mp 168°-169° (dec.); ³¹ P nmr (CD₃ SOCD₃) -20.0 ppm; ¹ H nmr δ9.5 (broad, ˜3, HO and HN), 3.5 (d, 2, J = 10Hz, CH₂ 2.9 (s, 3, CH₃), 2.6 (s, 3, CH₃).

Anal. Calcd for C₄ H₁₁ N₂ O₄ P: C, 26.38; H, 6.09; N, 15.38; P, 17.01. Found: C, 26.54; H, 6.16; N, 15.27; P, 17.17.

This phosphonic acid is prepared in a similar manner using tris(2-chloroethyl) phosphite as the phosphorus ester reactant. The intermediate ester, 1,4-dimethyl-2-(2-chloroethoxy)-1,4,2-diazaphospholidin-5-one-2-oxide (³¹ P nmr -24.9 ppm) is hydrolyzed from the reaction mixture to give the acid: mp 171°-172° dec (acetic acid-water).

EXAMPLE 20 1,4 -Dimethyl-3-(4-bromo-2-fluorphenyl)-2-(2-naphthyl)-1,4,2-diazaphospholidin-5-one-2-oxide ##SPC5##

When an equimolar mixture of diphenyl 2-napthylphosphonite, 4-bromo-2-fluorobenzaldehyde and 1,3-dimethylurea in toluene is warmed at reflux for one hour, followed by cooling in an ice bath, a white solid product forms. A portion of this solid is dissolved in ethanol and an equivalent amount of sodium hydroxide (10 molar solution) is added dropwise to the stirred solution. The reaction mixture is allowed to evaporate to dryness, and the residue is washed with ether, giving a crude sodium phosphinate salt. This salt is stirred in distilled water as slightly more than one equivalent of trifluoroacetic acid is added. The product is separated by filtration and then washed with water and recrystallized, giving [α-(1,3-dimethylureido)-4-bromo-2-fluorobenzyl]-2-naphthylphosphinic acid.

The nitrogen containing organophosphorous compounds of the present invention are useful as biological toxicants. The following examples illustrate the use of typical products.

Pre-emergent herbicidal activity of representative compounds of this invention is determined by the following procedure:

A good grade of top soil is placed in aluminum pans and compacted to a depth of 3/8 to 1/2 inch from the top of the pan. A pre-determined number of seeds of each of several plant species are placed on top of the soil in the pans. The seeds are covered with soil and the pans leveled. The herbicidal composition is applied by spryaing the surface of the top layer of soil with a solution containing a sufficient amount of active ingredient to obtain a rate of application of 10 lbs. per acre. The pans are then placed on a sand bench in the greenhouse and watered from below as needed. The plants are observed at the end of approximately 14 days and the results recorded.

Pre-emergent activity of the compounds prepared in the designated Examples is observed against the species as shown in the table below, wherein X denotes that herbicidal activity is observed.PRE-EMERGENT TESTINGCompound of Example 2 3 4 14______________________________________General Narrowleaf XGeneral Broadleaf X X XCanada Thistle X X XCocklebur X XVelvetleafMorning Glory XLambsquarters X XSmartweed X XQuackgrass X XJohnsongrass XDowny Brome XBarnyardgrass X______________________________________

EXAMPLE 21

The cyclic phosphorus esters of the present invention are useful as lead scavengers in leaded gasolines. For this purpose the esters are used in quantities of from 0.05 to 10 moles per mole of lead in the gasoline.

Another area of utility of the cyclic phosphorus esters of this invention is for fire-retardancey of paper. The test procedure is as follows: strips (6 inches by 2 inches) of paper (Whatman filter paper No. 3) are dried in an oven at 130°C. for 10 minutes and then weighed. The weighed strips of paper are placed in glass bottles containing about 50cc. of a solution of ethyl alcohol having 10 to 20% of the cyclic phosphorus ester. The bottles are tilted if necessary to cover the paper strips completely with impregnating solution. After one minute the paper is removed and pressed between two paper tissues with a 1000 gram weight. The paper strips are dried in air for 2 minutes and then in an oven at 130°C. for 10 minutes and weighed. The paper treated in this way usually contains from 5 to 15% of the additive ester chemical. Standard burning tests show that the samples having above about 10% of the additive cyclic phosphorus esters are significantly more resistant to burning than untreated control samples.

Fire retardant properties are obtained with:

1,4-Dimethyl-3-(4-hydroxy-3-methoxyphenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-Dimethyl-3-(2-furanyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-Dimethyl-2-(4-methylphenoxy)-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-Dimethyl-3(3,4 -dichlorophenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-thione-2-oxide.

2-(2-chloroethoxy)-1,4-dimethyl-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-dimethyl-3-phenyl-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.

2-(2-chloroethoxy)-1,4-dimethyl-3-(3-heptyl)-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-dimethyl-3-(2-methylthioethyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.

2-(2-chloroethoxy)-1,4-dimethyl-3-(2,6-dimethylhepta-1,5-dienyl)-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-dimethyl-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.

1,4-dimethyl-2-(2-chloroethoxy)-1,4,2-diazaphospholidin-5-one-2-oxide. 

What is claimed is:
 1. 1,4-dimethyl-3-(4-hydroxy-3-methoxyphenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide.
 2. 1,4-dimethyl-3-(2-furanyl)-2-phenoxy-1,4,2-diazaphospholidin-5-one-2-oxide. 3.1,4-dimethyl-2-(4-methylphenoxy)-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide.
 4. 1,4-dimethyl-3-(3,4-dichlorophenyl)-2-phenoxy-1,4,2-diazaphospholidin-5-thione-2-oxide.
 5. 2-(2-chloroethoxy-1,4-dimethyl-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide.
 6. 2-(2-chloroethoxy)-1,4-dimethyl-3-(3-heptyl)-1,4,2-diazaphospholidin-5-one-2-oxide.
 7. 2-(2-chloroethoxy)-1,4-dimethyl-3-(2,6-dimethylhepta-1,5-dienyl)-1,4,2-diazaphospholidin-5-one-2-oxide.
 8. 1,4-dimethyl-2-(2-chloroethoxy)-1,4,2-diazaphospholidin-5-one-2-oxide. 